Thumbs up on optimized beam target and horn design

Proposed target concept for LBNF mounted into Horn A. Beam enters from the left. (Image from CDR, Doc 4559)

In pursuit of a beam that will increase DUNE’s sensitivity to CP violation, three teams have been working together since 2015 on a conceptual-level optimized design for the LBNF beamline target, horns, and support systems. The design produced by the DUNE Beam Optimization Task Force (BOTF), the DUNE Accelerator Beam Interface Working Group (ABIWG), and the LBNF Beamline Project team passed its first review on October 5-6, 2017 at Fermilab.

The BOTF studies, completed last spring, concluded that a three-horn system with a longer (four-interaction-length) target embedded within the first horn would increase the neutrino flux at the Far Detector site and reduce the wrong-sign neutrino background, thereby resulting in a greater sensitivity to CP violation. The designs for the target and horn support infrastructures, the cooling systems, the horn power supply, the remote handling, the primary beam window and the upstream Decay Pipe beam window have also changed, in accordance with the engineering requirements that the task force imposed.

Schematic of the upstream portion of the LBNF neutrino beamline showing the major components. The target chase bulk steel shielding is shown mainly in green. Inside the target chase from left to right (the direction of the beam) pointing downwards: the beam window (not shown), horn-protection baffle, three focusing horns and the Decay Pipe. Watercooling panels start downstream of the target are shown in blue. (Image from CDR, Doc 4559)

The review was very successful, according to LBNF Project Manager Elaine McCluskey.

“LBNF/DUNE is to be commended on the extensive effort undertaken to study the optimized configuration,” the review committee wrote. “The basis for the fully optimized configuration is well motivated and the design, cost, and schedule developments are appropriately mature.”

With only a few specific technical recommendations (finding vendors for nickel plating and anodizing the horn conductors, and reviewing crane capacity), the committee found the materials presented at the review to be sufficient for moving straight away to a decision on whether to pursue the optimized configuration. The committee recommends pursuing the optimized design in its entirety. It also recommends proceeding with the redesign of the Absorber that the optimized configuration would require.

LBNF and DUNE leadership will discuss the recommendations at the next Experiment-Facility Interface Group (EFIG) meeting in November.

Related article: Interim report on beam optimization released (June 2016)